Many applications, such as, for example, mobile communications and mobile computing, generally require integrated circuits (ICs) with low power consumption in an effort to provide enhanced battery life of devices used in these applications. Such devices may include, but are not limited to, cell phones, portable storage devices, media player devices, portable computational devices, etc. In other applications, such as, for example, data processing and network communications, it would also be desirable to employ ICs with low power consumption so as to reduce packaging, cooling and/or board costs.
By way of illustration, the power associated with voltage swing of a capacitance, C, is a significant source of overall power consumption. Power, P, associated with a capacitance will increase with a square of the voltage, V, across the capacitance (e.g., P∝CV2f, where f is frequency). Other components of power consumption in an IC include, for example, subthreshold leakage through transistors and leakage through gate dielectric. In short channel transistors used today, subthreshold leakage increases with source-to-drain voltage. Transistor gate leakage also increases with voltage. Consequently, in order to reduce power consumption in the IC, it is desirable to reduce operating voltage in the IC.
Conventionally, the supply voltage level to a memory circuit can be increased in order to reduce the likelihood of failure in the memory circuit. In this manner, yield can be increased, but at the expense of increased power consumption in the memory circuit, which is undesirable, particularly for mobile applications. Alternatively, it is known to modify the design of memory cells and associated circuitry so that the memory circuit can operate at lower voltages. This approach, however, typically involves increasing the size of the memory cell and/or increasing complexity and component count, thereby increasing the cost of the memory device.
Accordingly, there exists a need for an improved memory circuit which does not suffer from one or more of the above-noted problems associated with conventional memory circuits.